| 摘要 |
PROBLEM TO BE SOLVED: To improve the mechanical strength of a pellet by using cement composition obtd. by heightening calcium content up to a specific range and pelletizing the powdery material. SOLUTION: A binder used for pelletizing the powdery material is the cement adjusted so as to contain 65.0-75.0 wt.% calcium in terms of CaO and 10.0-18.5 wt.% SiO2, 2.5-4.5 wt.% Al2O3 as the other components. In the case of using the ordinary Portland cement or blast furnace cement, calcium compound which can release Ca++ of calcium hydroxide, calcium carbonate, etc. is added by 65.0-75.0 wt.% (in terms of CaO). The object to be pelletized is particularly the powdery material containing iron of powdery iron, iron-containing dust, iron-containing sludge, etc. The granulated pellet by using the cement obtd. by heightening calcium content as the binder, is hardly crushed even in the case of piling, and further, at the time of charging into a converter as the iron raw material, the pellet is hardly crushed in a hopper and such accident as clogging of the hopper is hardly occurred.
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